Functional Contribution and Clinical Implication of Cancer-Associated Fibroblasts in Glioblastoma

PURPOSE

The abundance and biological contribution of cancer-associated fibroblasts (CAF) in glioblastoma (GBM) are poorly understood. Here, we aim to uncover its molecular signature, cellular roles, and potential tumorigenesis implications.

EXPERIMENTAL DESIGN

We first applied single-cell RNA sequencing (RNA-seq) and bioinformatics analysis to identify and characterize stromal cells with CAF transcriptomic features in human GBM tumors. Then, we performed functional enrichment analysis and in vitro assays to investigate their interactions with malignant GBM cells.

RESULTS

We found that CAF abundance was low but significantly correlated with tumor grade, poor clinical outcome, and activation of extracellular matrix remodeling using three large cohorts containing bulk RNA-seq data and clinical information. Proteomic analysis of a GBM-derived CAF line and its secretome revealed fibronectin (FN1) as a critical candidate factor mediating CAF functions. This was validated using in vitro cellular models, which demonstrated that CAF-conditioned media and recombinant FN1 could facilitate the migration and invasion of GBM cells. In addition, we showed that CAFs were more abundant in the mesenchymal-like state (or subtype) than in other states of GBMs. Interestingly, cell lines resembling the proneural state responded to the CAF signaling better for the migratory and invasive phenotypes.

CONCLUSIONS

Overall, this study characterized the molecular features and functional impacts of CAFs in GBM, alluding to novel cell interactions mediated by CAFs in the GBM microenvironment.

Bevacizumab and gamma knife radiosurgery for first-recurrence glioblastoma

INTRODUCTION

Glioblastoma (GBM) is the most common central nervous system malignancy in adults. Despite decades of developments in surgical management, radiation treatment, chemotherapy, and tumor treating field therapy, GBM remains an ultimately fatal disease. There is currently no definitive standard of care for patients with recurrent glioblastoma (rGBM) following failure of initial management.

OBJECTIVE

In this retrospective cohort study, we set out to examine the relative effects of bevacizumab and Gamma Knife radiosurgery on progression-free survival (PFS) and overall survival (OS) in patients with GBM at first-recurrence.

METHODS

We conducted a retrospective review of all patients with rGBM who underwent treatment with bevacizumab and/or Gamma Knife radiosurgery at Roswell Park Comprehensive Cancer Center between 2012 and 2022. Mean PFS and OS were determined for each of our three treatment groups: Bevacizumab Only, Bevacizumab Plus Gamma Knife, and Gamma Knife Only.

RESULTS

Patients in the combined treatment group demonstrated longer post-recurrence median PFS (7.7 months) and median OS (11.5 months) compared to glioblastoma patients previously reported in the literature, and showed improvements in total PFS (p=0.015), total OS (p=0.0050), post-recurrence PFS (p=0.018), and post-recurrence OS (p=0.0082) compared to patients who received either bevacizumab or Gamma Knife as monotherapy.

CONCLUSION

This study demonstrates that the combined use of bevacizumab with concurrent stereotactic radiosurgery can have improve survival in patients with rGBM.

Phase IIa Study of SurVaxM Plus Adjuvant Temozolomide for Newly Diagnosed Glioblastoma

PURPOSE

Despite intensive treatment with surgery, radiation therapy, temozolomide (TMZ) chemotherapy, and tumor-treating fields, mortality of newly diagnosed glioblastoma (nGBM) remains very high. SurVaxM is a peptide vaccine conjugate that has been shown to activate the immune system against its target molecule survivin, which is highly expressed by glioblastoma cells. We conducted a phase IIa, open-label, multicenter trial evaluating the safety, immunologic effects, and survival of patients with nGBM receiving SurVaxM plus adjuvant TMZ following surgery and chemoradiation (ClinicalTrials.gov identifier: NCT02455557).

METHODS

Sixty-four patients with resected nGBM were enrolled including 38 men and 26 women, in the age range of 20-82 years. Following craniotomy and fractionated radiation therapy with concurrent TMZ, patients received four doses of SurVaxM (500 μg once every 2 weeks) in Montanide ISA-51 plus sargramostim (granulocyte macrophage colony-stimulating factor) subcutaneously. Patients subsequently received adjuvant TMZ and maintenance SurVaxM concurrently until progression. Progression-free survival (PFS) and overall survival (OS) were reported. Immunologic responses to SurVaxM were assessed.

RESULTS

SurVaxM plus TMZ was well tolerated with no serious adverse events attributable to SurVaxM. Of the 63 patients who were evaluable for outcome, 60 (95.2%) remained progression-free 6 months after diagnosis (prespecified primary end point). Median PFS was 11.4 months and median OS was 25.9 months measured from first dose of SurVaxM. SurVaxM produced survivin-specific CD8+ T cells and antibody/immunoglobulin G titers. Apparent clinical benefit of SurVaxM was observed in both methylated and unmethylated patients.

CONCLUSION

SurVaxM appeared to be safe and well tolerated. The combination represents a promising therapy for nGBM. For patients with nGBM treated in this manner, PFS may be an acceptable surrogate for OS. A large randomized clinical trial of SurVaxM for nGBM is in progress.

Meta-analysis of overall survival and postoperative neurologic deficits after resection or biopsy of butterfly glioblastoma

Butterfly glioblastoma (bGBM) is a grade 4 glioma with a poor prognosis. Surgical treatment of these cancers has been reviewed in the literature with some recent studies supporting resection as a safe and effective treatment instead of biopsy and adjuvant therapy. This meta-analysis was designed to determine whether there are significant differences in overall survival (OS) and postoperative neurologic deficits (motor, speech, and cranial nerve) following intervention in patients who underwent tumor resection as part of their treatment, compared to patients who underwent biopsy without surgical resection. A literature search was conducted using PubMed (National Library of Medicine) and Embase (Elsevier) to identify articles from each database's earliest records to May 25, 2021, that directly compared the outcomes of biopsy and resection in bGBM patients and met predetermined inclusion criteria. A meta-analysis was conducted to compare the effects of the two management strategies on OS and postoperative neurologic deficits. Six articles met our study inclusion criteria. OS was found to be significantly longer for the resection group at 6 months (odds ratio [OR] 2.94, 95% confidence interval [CI] 1.23-7.05) and 12 months (OR 3.75, 95% CI 1.10-12.76) than for the biopsy group. No statistically significant differences were found in OS at 18 and 24 months. Resection was associated with an increased rate of postoperative neurologic deficit (OR 2.05, 95% CI 1.02-4.09). Resection offers greater OS up to 1 year postintervention than biopsy alone; however, this comes at the cost of higher rates of postoperative neurologic deficits.

INNV-14. PREDICTIVE UTILITY OF TEMOZOLOMIDE RESPONSE AS DETERMINED BY 3D EX-VIVO CELL CULTURE ASSAYS IN NEWLY DIAGNOSED GLIOBLASTOMA: A SINGLE INSTITUTION CASE SERIES EVALUATING PROGRESSION FREE SURVIVAL

Glioblastoma is an aggressive tumor that is clinically and pathologically heterogeneous, and as such, remains challenging to treat. Response to initial standard treatment is widely variable and patient specific. We describe a cohort of 11 newly diagnosed patients enrolled in the 3D-PREDICT study at a single institution who underwent maximal safe surgical resection with tumor tissue collected prospectively for ex vivo cell culture assays against a panel of commonly used agents, including temozolomide. Nine of eleven patients received concurrent radiation + temozolomide followed by adjuvant temozolomide as per current standard of care. Two patients progressed immediately following concurrent chemoradiation; pseudoprogression was ruled out with short interval repeat imaging and clinical deterioration with pathology confirming recurrent tumor on re-resection in one patient. Median follow-up was 10 months (range 2-18). Outcomes were assessed retrospectively using Kaplan-Meier time-to-event curves, separating into two groups the temozolomide responders (n=4) and temozolomide nonresponders (n=7), as defined by the previously validated assay. The event was reached when radiographic tumor recurrence/progression occurred. Due to limited sample size, statistical significance was not reached, but a trend toward longer time to recurrence was noted among the temozolomide responder group. Continued experience with this tool may help clinicians predict which patients with newly diagnosed glioblastoma will respond well to initial treatment with temozolomide and those that may be more appropriate for clinical trial enrollment, independent of MGMT promoter methylation status. Longer term studies with a larger number of patients will help to determine the true significance of this drug response prediction assay.

Prospective prediction of clinical drug response in high-grade gliomas using an ex vivo 3D cell culture assay

Background

Clinical outcomes in high-grade glioma (HGG) have remained relatively unchanged over the last 3 decades with only modest increases in overall survival. Despite the validation of biomarkers to classify treatment response, most newly diagnosed (ND) patients receive the same treatment regimen. This study aimed to determine whether a prospective functional assay that provides a direct, live tumor cell-based drug response prediction specific for each patient could accurately predict clinical drug response prior to treatment.

Methods

A modified 3D cell culture assay was validated to establish baseline parameters including drug concentrations, timing, and reproducibility. Live tumor tissue from HGG patients were tested in the assay to establish response parameters. Clinical correlation was determined between prospective ex vivo response and clinical response in ND HGG patients enrolled in 3D-PREDICT (ClinicalTrials.gov Identifier: NCT03561207). Clinical case studies were examined for relapsed HGG patients enrolled on 3D-PREDICT, prospectively assayed for ex vivo drug response, and monitored for follow-up.

Results

Absent biomarker stratification, the test accurately predicted clinical response/nonresponse to temozolomide in 17/20 (85%, P = .007) ND patients within 7 days of their surgery, prior to treatment initiation. Test-predicted responders had a median overall survival post-surgery of 11.6 months compared to 5.9 months for test-predicted nonresponders (P = .0376). Case studies provided examples of the clinical utility of the assay predictions and their impact upon treatment decisions resulting in positive clinical outcomes.

Conclusion

This study both validates the developed assay analytically and clinically and provides case studies of its implementation in clinical practice.

The Presence of Survivin on B Cells from Myasthenia Gravis Patients and the Potential of an Antibody to a Modified Survivin Peptide to Alleviate Weakness in an Animal Model

Myasthenia gravis (MG) is an autoimmune disease in which Abs target neuromuscular junction proteins, in particular the acetylcholine receptor. We previously identified the antiapoptotic protein survivin in the autoreactive B cells and plasma cells of MG patients. To further define the role of survivin in MG, we have assessed PBMCs from 29 patients with MG and 15 controls. We confirmed the increased expression of survivin in CD20⁺ lymphocytes from MG patients compared with controls. Furthermore, the CD20⁺ population of cells from MG patients contained a higher percentage of extracellular survivin compared with controls. The analysis of CD4⁺ cells showed an increased percentage of intracellular survivin in MG patients compared with controls, whereas the extracellular survivin CD4⁺ percentage was unaffected. In an experimental mouse model of MG, we assessed the therapeutic potential of an Ab raised to a modified survivin peptide but cross-reactive to survivin. Ab treatment reduced disease severity, lowered acetylcholine receptor-specific Abs, and decreased CD19⁺ survivin⁺ splenocytes. The ability to target survivin through Ab recognition of autoreactive cells offers the potential for a highly specific therapeutic agent for MG.

Black Bone Disease of the Skull

We present an image of a patient's skull characterized by dark, irregular discoloration. This was discovered incidentally in a 66-year-old man who underwent craniotomy for resection of a glioblastoma. This image demonstrates cranial black bone disease. This is an abnormal bone pigmentation associated with long-term tetracycline use, as occurred in this patient.

NCCN Guidelines Insights: Central Nervous System Cancers, Version 1.2017

For many years, the diagnosis and classification of gliomas have been based on histology. Although studies including large populations of patients demonstrated the prognostic value of histologic phenotype, variability in outcomes within histologic groups limited the utility of this system. Nonetheless, histology was the only proven and widely accessible tool available at the time, thus it was used for clinical trial entry criteria, and therefore determined the recommended treatment options. Research to identify molecular changes that underlie glioma progression has led to the discovery of molecular features that have greater diagnostic and prognostic value than histology. Analyses of these molecular markers across populations from randomized clinical trials have shown that some of these markers are also predictive of response to specific types of treatment, which has prompted significant changes to the recommended treatment options for grade III (anaplastic) gliomas.

Survivin Monoclonal Antibodies Detect Survivin Cell Surface Expression and Inhibit Tumor Growth In Vivo

Purpose: Survivin is an inhibitor of apoptosis protein (IAP) that is highly expressed in many cancers and represents an attractive molecule for targeted cancer therapy. Although primarily regarded as an intracellular protein with diverse actions, survivin has also been identified in association with circulating tumor exosomes.Experimental Design: We have reported that active, specific vaccination with a long peptide survivin immunogen leads to the development of survivin-specific CD8-mediated tumor cell lysis and prolongation of survival in tumor-bearing mice. In addition to cellular antitumor responses, circulating anti-survivin antibodies are detected in the serum of mice and human glioblastoma patients following vaccination with the survivin immunogen.Results: Here we demonstrate that survivin is present on the outer cell membrane of a wide variety of cancer cell types, including both murine and human glioma cells. In addition, antibodies to survivin that are derived from the immunogen display antitumor activity against murine GL261 gliomas in both flank and intracranial tumor models and against B16 melanoma as well.Conclusions: In addition to immunogen-induced, CD8-mediated tumor cell lysis, antibodies to the survivin immunogen have antitumor activity in vivo Cell-surface survivin could provide a specific target for antibody-mediated tumor immunotherapeutic approaches. Clin Cancer Res; 24(11); 2642-52. ©2018 AACR.

Impact of the Number of Metastatic Tumors Treated by Stereotactic Radiosurgery on the Dose to Normal Brain: Implications for Brain Protection

PURPOSE/OBJECTIVES

The purpose of this study was to evaluate the effect of the number of brain lesions for which stereotactic radiosurgery (SRS) was performed on the dose volume relationships in normal brain.

MATERIALS AND METHODS

Brain tissue was segmented using the patient's pre-SRS MRI. For each plan, the following data points were recorded: total brain volume, number of lesions treated, volume of brain receiving 8 Gy (V8), V10, V12, and V15.

RESULTS

A total of 225 Gamma Knife® treatments were included in this retrospective analysis. The number of lesions treated ranged from 1 to 29. The isodose for prescription ranged from 40 to 95% (mean 55%). The mean prescription dose to tumor edge was 18 Gy. The mean coverage, selectivity, conformity, and gradient index were 97.5%, 0.63, 0.56, and 3.5, respectively. The mean V12 was 9.5 cm3 (ranging from 0.5 to 59.29). There was no correlation between the number of lesions and brain V8, V12, V10, or V15. There was a direct and statistically significant relationship between the brain volume treated (V8, V10, V12, and V15) and total volume of tumors treated (p < 0.001). In our study, the integral dose to the brain exceeded 3 J when the total tumor volume exceeded 25 cm3.

CONCLUSIONS

The number of metastatic brain lesions treated bears no significant relationship to total brain tissue volume treated when using SRS. The fact that the integral dose to the brain exceeded 3 J when the total tumor volume exceeded 25 cm3 is useful for establishing guidelines. Although standard practice has favored using whole brain radiation therapy in patients with more than 4 lesions, a significant amount of normal brain tissue may be spared by treating these patients with SRS. SRS should be carefully considered in patients with multiple brain lesions, with the emphasis on total brain volume involved rather than the number of lesions to be treated.

Circulating CD9+/GFAP+/survivin+ exosomes in malignant glioma patients following survivin vaccination

Glioma cells release exosomes in culture and into the extracellular matrix in vivo. These nanobodies transport an array of biomolecules and are capable of mediating cell-cell communication. Circulating exosomes in cancer patients may be indicative of disease status and response to therapy. The inhibitor of apoptosis protein (IAP) survivin (SVN) promotes cancer cell proliferation, local immune suppression and resistance to chemotherapy and it is a potential cancer biomarker. We used imaging flow cytometry to perform quantitative measurements of circulating SVN+ exosomes in the serum of malignant glioma patients undergoing investigational treatment with an anti-survivin vaccine (SurVaxM). Serum from glioma patients contained abundant CD9+ exosomes with both SVN and glial fibrillary acidic protein (GFAP) on their surface. Survivin and GFAP were evaluated both independently and together as possible tumor markers on CD9+ exosomes. Patients with longer time to tumor progression generally exhibited a decrease in circulating CD9+/SVN+ and CD9+/GFAP+/SVN+ exosomes immediately following survivin vaccination; whereas, those with early tumor progression had an increase in exosomes, despite anti-survivin immunotherapy. Serum from non-cancer healthy control individuals had very few detectable CD9+/GFAP+/SVN+ exosomes, although CD9+/GFAP+ exosomes were detectable in small numbers. This study demonstrates that patients with malignant gliomas have CD9+/GFAP+/SVN+ and CD9+/SVN+ exosomes that are released into the circulation and that early reductions in their numbers following anti-survivin immunotherapy might be associated with longer progression-free survival.

Immunotherapeutic Strategies for Malignant Glioma

BACKGROUND

Despite advances in surgery, radiation therapy, and chemotherapy, only modest improvement has been achieved in the survival of patients with malignant gliomas.

METHODS

The authors review the immunologic aspects of gliomas, potential targets for therapy, and issues surrounding current immunotherapeutic strategies directed against malignant gliomas.

RESULTS

The blood-brain barrier and the purported immunological privilege of the brain are not necessarily insurmountable obstacles to effective immunotherapy for brain tumors. Preclinical studies suggest a number of potential therapeutic avenues. Translational studies offer the prospect of providing substantial new information about immunological trafficking in the nervous system and suggesting the most fruitful approaches to immunotherapy for malignant gliomas.

CONCLUSIONS

More effective adjuvant treatments for malignant gliomas are needed. The applicability of immunological approaches in the treatment of these tumors warrants continued study.

Novel vaccines for glioblastoma: clinical update and perspective

Glioblastoma is the most common primary brain cancer. Aggressive treatment with surgery, radiation therapy and chemotherapy provides limited overall survival benefit. Glioblastomas have a formidable tumor microenvironment that is hostile to immunological effector cells and these cancers produce profound systemic immunosuppression. However, surgical resection of these tumors creates conditions that favor the use of immunotherapeutic strategies. Therefore, extensive surgical resection, when feasible, will remain part of the equation to provide an environment in which active specific immunotherapy has the greatest chance of working. Toward that end, a number of vaccination protocols are under investigation. Vaccines studied to date have produced cellular and humoral antitumor responses, but unequivocal clinical efficacy has yet to be demonstrated. In addition, focus is shifting toward the prospect of therapies involving vaccines in combination with immune checkpoint inhibitors and other immunomodulatory agents so that effector cells remain active against their targets systemically and within the tumor microenvironment.

Abstract 4689: Anti-proliferative effect and tumor targeting properties of SurVaxM-derived monoclonal antibodies

Background: Survivin is an inhibitor of apoptosis protein (IAP) which is upregulated in many cancers. SurVaxM (active anti-survivin immunotherapy) is currently being evaluated in a multi-center phase II clinical trial. Circulating anti-survivin antibodies were recently detected in recurrent glioblastoma patients who received SurVaxM immunizations in a previous phase I study. Though primarily functioning as an intracellular molecule, survivin has also been identified in patient serum, and, recently, in tumor-derived exosomes.

Methods: Patients in the completed SurVaxM phase I clinical trial produced both antibody and CD8+ T cell responses against survivin. In order to gauge whether antibodies to the vaccine provided any therapeutic benefit, or might serve as potential biomarkers for SurVaxM responsiveness, we tested these antibodies in pre-clinical tumor models. Murine hybridomas derived from the SurVaxM peptide were established and purified yielding several high-affinity IgG antibodies. These antibodies were characterized for target recognition and therapeutic potential.

Results: Two of the clones with the highest affinities, 2C2 (IgG2a) and H30 (IgG1), recognized both SurVaxM peptide and the wild type survivin counterpart (ELISA assay), as well as endogenous, full-length survivin (western blotting). Survivin was detected on cells with these antibodies using both immunofluorescence and flow cytometry. Following s.c. implantation of glioblastoma (GL261) and melanoma (B16) tumors in immuno-competent C57BL/6 mice, administration of 2C2 and H30 antibodies (i.p. injection) reduced tumor growth in both models compared to an irrelevant IgG. An orthotopic intracranial glioma study showed similar anti-tumor effects when treated with SurVaxM-derived antibodies. Tumor growth was also inhibited in immuno-compromised (nude) animals treated with 2C2 or H30 antibodies, although to a lesser extent.

Conclusions: Antibodies generated in response to the SurVaxM vaccination are highly cross-reactive to survivin and provide therapeutic benefit in immuno-competent mouse tumor models. These antibodies retain some efficacy in immuno-compromised models, indicative of a direct T-cell independent effect. An anti-tumor response through anti-survivin targeted antibodies is unexpected as surface-accessible survivin expression has not yet been well described in the literature. Data presented here highlight possible avenues for investigation of mechanism(s) of action.

Citation Format: Michael J. Ciesielski, Sheila Figel, Laura Wiltsie, Phillip Galbo, Cheryl Frank, Robert A. Fenstermaker. Anti-proliferative effect and tumor targeting properties of SurVaxM-derived monoclonal antibodies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4689. doi:10.1158/1538-7445.AM2017-4689

Abstract 2725: Circulating CD9-GFAP-survivin exosomes during active specific immunotherapy, a potential biomarker for glioma

Background: We evaluated circulating exosomes isolated from the serum of malignant glioma patients enrolled in a completed phase I clinical trial of an anti-survivin vaccine (SurVaxM). Exosomes are microvesicular bodies with potential mechanisms for cell-cell communication. Identifying circulating exosomes from cancer patients as potential indicators of disease status and response to therapy is of interest. The inhibitor of apoptosis protein (IAP) survivin (SVN) promotes cancer cell proliferation and resistance to chemotherapy. Survivin is expressed in many cancer types including malignant gliomas and is a potential target for active immunotherapy. In the above mentioned clinical trial, five patients experienced early tumor progression with a mean of 2.8 months (1.9-5.4 months) from study entry, while three patients had either late (20.5-22.5 months) or no tumor progression (no evident disease at 48 months in one patient).

Methods: To determine whether changes in CD9+/GFAP+/SVN+ exosomes correlated with disease progression, patient serum was evaluated prior to treatment (study entry), 8-10 weeks after initial vaccination, and at the time of MRI-defined tumor progression. By employing ImageStream flow cytometry technology we were able to analyze multiple markers on individual exosomes, identifying highly specific populations of survivin+ exosomes which co-expressed the brain/tumor marker protein GFAP. The combination of these markers made it possible to differentiate patient exosomes from those of healthy individuals.

Results: The levels of CD9+/GFAP+, CD9+/SVN+, and CD9+/GFAP+/SVN+ (SVN+) exosomes were significantly increased in patients. Serum from three patients who experienced the longest progression-free intervals, showed 98-99% decreases in SVN+ exosomes after treatment with SurVaxM, and maintained similarly low exosome levels over several months. Five early progressing patients experienced a detectable persistence of, or increase in SVN+ exosomes at 9 weeks following initial vaccination. One patient had rising SVN+ exosomes detectable 16 weeks prior to the discovery of tumor progression by brain MRI scan. One patient with no tumor progression sustained a 99% reduction in serum SVN+ exosomes which was sustained over 48+ months.

Conclusion: This study demonstrates that increased numbers of CD9+/GFAP+/SVN+ specific exosomes appear to be associated with early tumor progression in recurrent malignant glioma patients. Larger studies are needed to determine whether the correlation between SVN+ exosome levels and disease progression is specific to SurVaxM treatment, and whether rises in SVN+ exosomes levels are predictive of generalized glioma progression. Our study suggests that levels of circulating SVN+ exosomes may be altered during anti-survivin immunotherapy and could serve as a potential biomarker for clinical trials and tumor monitoring.

Citation Format: Michael J. Ciesielski, Phillip Galbo, Sheila Figel, Laura Wiltsie, Cheryl Frank, Jingxin Qiu, Robert A. Fenstermaker. Circulating CD9-GFAP-survivin exosomes during active specific immunotherapy, a potential biomarker for glioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2725. doi:10.1158/1538-7445.AM2017-2725

Central Nervous System Cancers, Version 1.2015

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Central Nervous System (CNS) Cancers provide interdisciplinary recommendations for managing adult CNS cancers. Primary and metastatic brain tumors are a heterogeneous group of neoplasms with varied outcomes and management strategies. These NCCN Guidelines Insights summarize the NCCN CNS Cancers Panel's discussion and highlight notable changes in the 2015 update. This article outlines the data and provides insight into panel decisions regarding adjuvant radiation and chemotherapy treatment options for high-risk newly diagnosed low-grade gliomas and glioblastomas. Additionally, it describes the panel's assessment of new data and the ongoing debate regarding the use of alternating electric field therapy for high-grade gliomas.

Papillary tumor of the pineal region with extended clinical and radiologic follow-up

BACKGROUND

Papillary tumor of the pineal region (PTPR) is a rare neoplasm with only anecdotal data to guide the treatment. Results of treatment with surgery, radiation therapy, and chemotherapy have been reported to have varying degrees of success. Here we report a patient with a PTPR, who underwent subtotal resection, gamma knife stereotactic radiosurgery, and adjuvant temozolomide chemotherapy.

CASE DESCRIPTION

During 9 years of clinical and radiographic follow-up, the patient has had regression of residual tumor and remains asymptomatic.

CONCLUSION

When gross total resection of a PTPR is not possible, treatment with gamma knife stereotactic radiosurgery and temozolomide chemotherapy may provide long-term tumor control.

Central nervous system cancers, version 2.2014. Featured updates to the NCCN Guidelines

The NCCN Guidelines for Central Nervous System Cancers provide multidisciplinary recommendations for the clinical management of patients with cancers of the central nervous system. These NCCN Guidelines Insights highlight recent updates regarding the management of metastatic brain tumors using radiation therapy. Use of stereotactic radiosurgery (SRS) is no longer limited to patients with 3 or fewer lesions, because data suggest that total disease burden, rather than number of lesions, is predictive of survival benefits associated with the technique. SRS is increasingly becoming an integral part of management of patients with controlled, low-volume brain metastases.

Challenges in the development of a survivin vaccine (SurVaxM) for malignant glioma

There is growing interest in immunotherapy for malignant gliomas. This interest stems from a number of immunological observations, together with the failure of conventional therapeutic agents to produce broad and clinically meaningful improvements in survival and quality of life. The challenges faced in translating laboratory-based immunological observations to Phase I and II clinical trials for immunotherapy of gliomas are substantial. Nevertheless, as our understanding of the effects of active specific vaccination in glioma patients grows, results support optimism that such methods may eventually prove useful as an adjunctive treatment for these cancers. This paper highlights a number of barriers encountered in the translational development of a survivin-targeted peptide vaccine (SurVaxM) for patients with malignant gliomas.

Survivin as a potential mediator to support autoreactive cell survival in myasthenia gravis: a human and animal model study

The mechanisms that underlie the development and maintenance of autoimmunity in myasthenia gravis are poorly understood. In this investigation, we evaluate the role of survivin, a member of the inhibitor of apoptosis protein family, in humans and in two animal models. We identified survivin expression in cells with B lymphocyte and plasma cells markers, and in the thymuses of patients with myasthenia gravis. A portion of survivin-expressing cells specifically bound a peptide derived from the alpha subunit of acetylcholine receptor indicating that they recognize the peptide. Thymuses of patients with myasthenia gravis had large numbers of survivin-positive cells with fewer cells in the thymuses of corticosteroid-treated patients. Application of a survivin vaccination strategy in mouse and rat models of myasthenia gravis demonstrated improved motor assessment, a reduction in acetylcholine receptor specific autoantibodies, and a retention of acetylcholine receptor at the neuromuscular junction, associated with marked reduction of survivin-expressing circulating CD20+ cells. These data strongly suggest that survivin expression in cells with lymphocyte and plasma cell markers occurs in patients with myasthenia gravis and in two animal models of myasthenia gravis. Survivin expression may be part of a mechanism that inhibits the apoptosis of autoreactive B cells in myasthenia gravis and other autoimmune disorders.

Central nervous system cancers

Primary and metastatic tumors of the central nervous system are a heterogeneous group of neoplasms with varied outcomes and management strategies. Recently, improved survival observed in 2 randomized clinical trials established combined chemotherapy and radiation as the new standard for treating patients with pure or mixed anaplastic oligodendroglioma harboring the 1p/19q codeletion. For metastatic disease, increasing evidence supports the efficacy of stereotactic radiosurgery in treating patients with multiple metastatic lesions but low overall tumor volume. These guidelines provide recommendations on the diagnosis and management of this group of diseases based on clinical evidence and panel consensus. This version includes expert advice on the management of low-grade infiltrative astrocytomas, oligodendrogliomas, anaplastic gliomas, glioblastomas, medulloblastomas, supratentorial primitive neuroectodermal tumors, and brain metastases. The full online version, available at NCCN. org, contains recommendations on additional subtypes.

Cranial base repair with combined vascularized nasal septal flap and autologous tissue graft following expanded endonasal endoscopic neurosurgery

BACKGROUND

The expanded endonasal endoscopic approach provides excellent visualization and access to midline skull base lesions, albeit with a relatively high risk of postoperative cerebrospinal fluid (CSF) leakage. We present our experience with the expanded endonasal endoscopic approach to the skull base in an institution where, previously, a traditional transsphenoidal approach with a surgical microscope had been used.

PATIENTS

We performed a retrospective review to identify patients who underwent expanded endonasal endoscopic surgery and analyzed demographic, pathological, and operative data with particular attention to repair of the skull base defects in 55 procedures performed on 49 patients. We compared the outcomes of 10 primary operations in which we repaired skull base defects using only autologous or allogeneic tissue grafts and 39 primary operations in which we used a vascularized mucoperichondrial nasal septal flap with or without a layered autologous tissue graft.

RESULTS

Primary expanded endonasal endoscopic procedures were performed in 49 patients with sellar pathology (33 pituitary adenomas, 4 Rathke's cleft cysts, 1 pituicytoma, 1 pituitary metastasis) and non-sellar pathology (3 meningiomas, 3 clival chordomas, 1 clival mucocele, 1 craniopharyngioma, and 2 esthesioneuroblastomas). Postoperative CSF leakage occurred following 5 of the 49 primary operations (10.2%). This occurred in 2 of 10 primary operations (20.0%) in which the skull base defect was repaired using only autologous and/or allogeneic tissue grafts, necessitating a total of 3 operative CSF leak repairs in those 2 patients. The remaining 3 postoperative CSF leaks occurred in the 39 primary operations (7.7%) in which skull base repair was performed using a mucoperichondrial nasal septal flap, necessitating operative repair in 2 of those patients.

CONCLUSION

The repair of skull base defects created during expanded endonasal endoscopic surgery is improved by use of a mucoperichondrial nasal septal flap combined with a layered autologous tissue graft. When CSF leakage occurs despite nasal septal flap closure, the site of the leakage may be easier to localize and repair.

Intracranial meningiomas in patients with uterine sarcoma treated with long-term megestrol acetate therapy

OBJECTIVE

To report a series of four patients with uterine sarcoma, including one with müllerian adenosarcoma (MA) and three with low-grade endometrial stromal sarcoma (LGESS), who developed intracranial meningiomas while receiving the progesterone agonist megestrol acetate.

METHODS

The hospital records, imaging studies, and pathology slides of four patients who were treated for uterine sarcomas and subsequently developed intracranial meningiomas were reviewed.

RESULTS

All patients underwent surgery for their gynecologic cancers and received maintenance therapy with long-term hormonal suppression with megestrol acetate. Each of the four patients later developed neurologic symptoms secondary to intracranial meningiomas. Three patients had more than one meningioma. Histopathologic examination of all excised tumors showed strong immunoreactivity for progesterone receptors (PRs).

CONCLUSIONS

Patients with uterine sarcoma subtypes LGESS and MA may be predisposed to develop meningiomas, particularly in the setting of long-term treatment with megestrol acetate. Alternatively, preexisting, clinically silent meningiomas in these patients may have progressed to the point of clinical symptoms in the presence of the progesterone agonist megestrol acetate. Without previous imaging studies showing the presence or absence of meningioma before initiation of megestrol acetate treatment, there is no way to draw definitive conclusions regarding this possibility. Clinical and neuroradiologic surveillance for meningiomas should be strongly considered in patients with these uterine sarcoma subtypes, particularly in patients undergoing long-term suppressive therapy with megestrol acetate.

Metastasis suppressor NM23-H1 promotes repair of UV-induced DNA damage and suppresses UV-induced melanomagenesis

Reduced expression of the metastasis suppressor NM23-H1 is associated with aggressive forms of multiple cancers. Here, we establish that NM23-H1 (termed H1 isoform in human, M1 in mouse) and two of its attendant enzymatic activities, the 3'-5' exonuclease and nucleoside diphosphate kinase, are novel participants in the cellular response to UV radiation (UVR)-induced DNA damage. NM23-H1 deficiency compromised the kinetics of repair for total DNA polymerase-blocking lesions and nucleotide excision repair of (6-4) photoproducts in vitro. Kinase activity of NM23-H1 was critical for rapid repair of both polychromatic UVB/UVA-induced (290-400 nm) and UVC-induced (254 nm) DNA damage, whereas its 3'-5' exonuclease activity was dominant in the suppression of UVR-induced mutagenesis. Consistent with its role in DNA repair, NM23-H1 rapidly translocated to sites of UVR-induced (6-4) photoproduct DNA damage in the nucleus. In addition, transgenic mice hemizygous-null for nm23-m1 and nm23-m2 exhibited UVR-induced melanoma and follicular infundibular cyst formation, and tumor-associated melanocytes displayed invasion into adjacent dermis, consistent with loss of invasion-suppressing activity of NM23 in vivo. Taken together, our data show a critical role for NM23 isoforms in limiting mutagenesis and suppressing UVR-induced melanomagenesis.

EGFR Intron Recombination in Human Gliomas: Inappropriate Diversion of V(D)J Recombination?

The epidermal growth factor receptor (EGFR) is a membrane-bound, 170 kDa, protein tyrosine kinase that plays an important role in tumorigenesis. The EGFR gene, which is composed of over 168 kb of sequence, including a 123-kb first intron, is frequently amplified and rearranged in malignant gliomas leading to the expression of oncogenic deletion (DM) and tandem duplication (TDM) mutants. The most common DM in gliomas is EGFRvIII, which arises from recombination between introns 1 and 7 with deletion of exons 2 through 7 and intervening introns. In addition, some human gliomas express 180- to 190-kDa TDM, which are constitutively active and highly oncogenic. Both DM and TDM arise by recombination of introns that contain sequences with homology to the recombination signal sequence (RSS) heptamers and nonamers present in the V(D)J region of the immunoglobin and T lymphocyte antigen receptor genes. V(D)J RSS have also been identified in certain proto-oncogenes like bcl-2 that are involved in translocations associated with the development of human lymphomas and in other genes such as hypoxanthine-guainine phosphoribosyl transferase (HPRT) in which deletion mutations and intron rearrangements are a common phenomenon. Together with the expression of recombination associated gene (RAG) and nonhomologous end-joining (NHEJ) proteins in gliomas, these observation suggest that aberrant activity of the V(D)J recombinase may be involved in the activation of proto-oncogenes in both liquid and solid tumors.

Endoscopic sellar floor reconstruction with concha bullosa bone autograft and nasal septal flap: technical case report

INTRODUCTION

A novel method is introduced for sellar floor reconstruction after expanded endoscopic endonasal transsphenoidal surgery using concha bullosa bone autograft and vascularized, posteriorly based flaps of septal mucoperichondrium.

CASE REPORT

A 62-year-old woman presented to her primary care physician with the insidious onset of enlarging hands and feet, coarsening of facial features, and bilateral carpal tunnel syndrome. Endocrine studies revealed elevated growth hormone (22 ng/mL) and somatomedian-C (810 ng/mL) levels. Brain magnetic resonance imaging displayed a 1.2-cm pituitary adenoma. The patient was diagnosed with acromegaly secondary to a pituitary adenoma and underwent expanded endoscopic endonasal transsphenoidal surgery for tumor resection. Preoperatively, the patient was noted to have abnormal right middle turbinate pneumatization (concha bullosa). Following adenoma resection, the sellar floor was reconstructed using concha bullosa bone autograft resected during the endonasal approach. Bilateral vascularized nasoseptal mucosal flaps were then placed over the sellar floor.

CONCLUSION

In patients with concha bullosa, conchal bone provides a useful substrate for sellar reconstruction after endoscopic endonasal transsphenoidal surgery.

Immunization with a mimotope of GD2 ganglioside induces CD8+ T cells that recognize cell adhesion molecules on tumor cells

The GD2 ganglioside expressed on neuroectodermal tumor cells has been used as a target for passive and active immunotherapy in patients with malignant melanoma and neuroblastoma. We have reported that immunization of mice with a 47-LDA mimotope of GD2, isolated from a phage display peptide library with anti-GD2 mAb 14G2a, induces MHC class I-restricted CD8(+) T cell responses to syngeneic neuroblastoma tumor cells. The cytotoxic activity of the vaccine-induced CTLs was independent of GD2 expression, suggesting recognition of a novel tumor-associated Ag cross-reacting with 47-LDA. Glycan microarray and immunoblotting studies using 14G2a mAb demonstrated that this Ab is highly specific for the entire carbohydrate motif of GD2 but also cross-reacts with a 105 kDa glycoprotein expressed by GD2(+) and GD2(-) neuroblastoma and melanoma cells. Functional studies of tumor cells grown in three-dimensional collagen cultures with 14G2a mAb showed decreases in matrix metalloproteinase-2 activation, a process regulated by the 105 kDa-activated leukocyte cell adhesion molecule (ALCAM/CD166). A recombinant CD166 glycoprotein was shown to be recognized by 14G2a Ab and inhibition of CD166 expression by RNA interference ablated the cell sensitivity to lysis by 47-LDA-induced CD8(+) T cells in vitro and in vivo. The binding of 14G2a to CD166 was not disruptable by a variety of exo- and endo-glycosidases, implying recognition of a non-glycan epitope on CD166. These results suggest that the vaccine-induced CTLs recognize a 47-LDA cross-reactive epitope expressed by CD166, and reveal a novel mechanism of induction of potent tumor-specific cellular responses by mimotopes of tumor-associated carbohydrate Ags.

Expression of HMP/AN2, a melanoma associated antigen, in murine cerebral gliomas: potential for radioimmunotargeting

Human melanoma proteoglycan (HMP), a melanoma-associated antigen, is expressed in both human melanomas and gliomas. We used HMP-specific monoclonal antibody (mAb) VT68.2 to investigate whether murine GL261 cerebral gliomas express the HMP homologue AN2 and to determine whether AN2 could be targeted for selective delivery of radiation in vivo. HMP-specific mAb VT68.2 stained murine GL261 glioma cells grown in culture and intracerebrally in syngeneic C57BL/6 mice. Positron emission tomography with radiolabeled mAb VT68.2 showed high-contrast, positive images of gliomas against a negative background. At 96 h after injection, glioma uptake of radiolabeled mAb VT68.2 was 10x greater than that of the isotype control mAb and 20x greater than that detected in normal cerebral tissue. Our results show murine GL261 cerebral gliomas express AN2 and HMP-specific mAb VT68.2 accumulates selectively and specifically at high concentration and is retained within murine cerebral gliomas. Thus, HMP is a potential target for antibody-mediated selective delivery of radiation to cerebral gliomas in vivo.

Therapeutic effect of a T helper cell supported CTL response induced by a survivin peptide vaccine against murine cerebral glioma

Survivin is a tumor-associated antigen (TAA) that has significant potential for use as a cancer vaccine target. To identify survivin epitopes that might serve as targets for CTL-mediated, anti-tumor responses, we evaluated a series of survivin peptides with predicted binding to mouse H2-K(b) and human HLA-A*0201 antigens in peptide-loaded dendritic cell (DC) vaccines. H2-K(b)-positive, C57BL/6 mice were vaccinated using syngeneic, peptide-loaded DC2.4 cells. Splenocytes from vaccinated mice were screened by flow cytometry for binding of dimeric H2-K(b):Ig to peptide-specific CD8+ T cells. Two survivin peptides (SVN(57-64) and SVN(82-89)) generated specific CD8+ T cells. We chose to focus on the SVN(57-64) peptide because that region of the molecule is 100% homologous to human survivin. A larger peptide (SVN(53-67)), containing multiple class I epitopes, and a potential class II ligand, was able to elicit both CD8+ CTL and CD4+ T cell help. We tested the SVN(53-67) 15-mer peptide in a therapeutic model using a peptide-loaded DC vaccine in C57BL/6 mice with survivin-expressing GL261 cerebral gliomas. This vaccine produced significant CTL responses and helper T cell-associated cytokine production, resulting in a significant prolongation of survival. The SVN(53-67) vaccine was significantly more effective than the SVN(57-64) core epitope as a cancer vaccine, emphasizing the potential benefit of incorporating multiple class I epitopes and associated cytokine support within a single peptide.

Intratumoral hemorrhage after remote subtotal microsurgical resection and gamma knife radiosurgery for vestibular schwannoma

Our report describes the occurrence of intratumoral hemorrhage in a vestibular schwannoma, which was treated with microsurgical resection thirteen years and gamma knife surgery (GKS) more than two years prior to the event. Although rare, it is apparent that bleeding into a vestibular schwannoma remains a possibility, even after the tumor has responded favorably to GKS. Long-term followup of patients with vestibular schwannoma who have been treated with GKS is advisable to assess treatment response and to detect adverse events (e.g. hemorrhage) suspected on clinical grounds.

Molecular Targeting and Treatment of an Epidermal Growth Factor Receptor-Positive Glioma Using Boronated Cetuximab

PURPOSE

The purpose of the present study was to evaluate the anti-epidermal growth factor monoclonal antibody (mAb) cetuximab (IMC-C225) as a delivery agent for boron neutron capture therapy (BNCT) of a human epidermal growth factor receptor (EGFR) gene-transfected rat glioma, designated as F98(EGFR).

EXPERIMENTAL DESIGN

A heavily boronated polyamidoamine dendrimer was chemically linked to cetuximab by means of the heterobifunctional reagents N-succinimidyl 3-(2-pyridyldithio)-propionate and N-(k-maleimido undecanoic acid)-hydrazide. The bioconjugate, designated as BD-C225, was specifically taken up by F98(EGFR) glioma cells in vitro compared with receptor-negative F98 wild-type cells (41.8 versus 9.1 microg/g). For in vivo biodistribution studies, F98(EGFR) cells were implanted stereotactically into the brains of Fischer rats, and 14 days later, BD-C225 was given intracerebrally by either convection enhanced delivery (CED) or direct intratumoral (i.t.) injection.

RESULTS

The amount of boron retained by F98(EGFR) gliomas 24 h following CED or i.t. injection was 77.2 and 50.8 microg/g, respectively, with normal brain and blood boron values <0.05 mug/g. Boron neutron capture therapy was carried out at the Massachusetts Institute of Technology Research Reactor 24 h after CED of BD-C225, either alone or in combination with i.v. boronophenylalanine (BPA). The corresponding mean survival times (MST) were 54.5 and 70.9 days (P = 0.017), respectively, with one long-term survivor (more than 180 days). In contrast, the MSTs of irradiated and untreated controls, respectively, were 30.3 and 26.3 days. In a second study, the combination of BD-C225 and BPA plus sodium borocaptate, given by either i.v. or intracarotid injection, was evaluated and the MSTs were equivalent to that obtained with BD-C225 plus i.v. BPA.

CONCLUSIONS

The survival data obtained with BD-C225 are comparable with those recently reported by us using boronated mAb L8A4 as the delivery agent. This mAb recognizes the mutant receptor, EGFRvIII. Taken together, these data convincingly show the therapeutic efficacy of molecular targeting of EGFR using a boronated mAb either alone or in combination with BPA and provide a platform for the future development of combinations of high and low molecular weight delivery agents for BNCT of brain tumors.

Antitumor effects of a xenogeneic survivin bone marrow derived dendritic cell vaccine against murine GL261 gliomas

Survivin is a member of the inhibitor of apoptosis protein family. Gliomas and many other tumors express survivin at high levels; whereas, normal fully differentiated cells generally do not. Therefore, survivin represents a tumor-specific target for cancer vaccine therapy. It has been shown that it is possible to produce a MHC-I-restricted cellular immunologic response to survivin vaccines. To study differences in immunogenicity between murine and human survivin proteins, we vaccinated C57BL/6 mice with bone marrow dendritic cells (BMDC) transfected with expression vectors containing the murine and human survivin genes. Mice vaccinated with BMDCs expressing a truncated human survivin protein developed cytotoxic T lymphocyte to subcutaneous GL261 glioma cells and exhibited prolonged tumor-free survival compared to mice vaccinated with BMDCs transfected with vector alone (P<0.01). While mice challenged with intracerebral GL261 cells had increased survival, no cures were observed. In contrast, vaccinated mice that fully resisted subcutaneous tumor challenge were rendered resistant to intracerebral GL261 re-challenge. BMDCs transfected with the full-length human survivin molecule were significantly more effective at prolonging survival than BMDCs expressing the full-length murine survivin gene (P=0.0175). Therefore, xenogeneic differences between human and murine sequences might be exploited to develop more immunogenic tumor vaccines.

Cell-surface receptor for thyroid hormone and tumor cell proliferation

Integrin αVβ3 is a structural protein of the plasma membrane that transduces signals from extracellular matrix proteins and has recently been shown to contain a novel receptor for thyroid hormone. Thyroid hormone signals are converted by αVβ3 into mitogen-activated protein kinase (MAPK) (ERK1/2) activation and downstream intracellular events in the cell nucleus. The latter include post-translational modification of the nuclear thyroid hormone receptor (TRβ1) and complex cellular or tissue responses, such as hormone-induced angiogenesis via basic fibroblast growth factor release. The integrin receptor for thyroid hormone has been shown to mediate proliferative effects of the hormone on certain tumor cell lines, including murine glioma/glioblastoma cells and human breast cancer (MCF-7) cells. More than one mechanism may account for this hormonal action, but in vitro studies indicate a direct hormonal action on cellular proliferation. Other possible mechanisms involve indirect actions via the release of tumor growth factors and effects on cell migration. In the intact organism, support of tumor growth by thyroid hormone is postulated to include angiogenesis. Crosstalk between the integrin thyroid hormone receptor and the epidermal growth factor receptor on the plasma membrane may be another mechanism by which thyroid hormone may modify tumor cell growth. Tetraiodothyroacetic acid (tetrac) is an iodothyronine analog that has no agonist activity at the integrin receptor, but inhibits binding of l-thyroxine and 3,5,3´-triiodo-l-thyronine to the receptor, preventing MAPK activation and consequent actions downstream of MAPK. In vitro studies and a preliminary in vivo experiment indicate that tetrac blocks the action of thyroid hormone on tumor cell proliferation. Both unmodified tetrac and tetrac reformulated as a nanoparticle that does not gain access to the cell interior are under investigation in animal models as anticancer agents. Also under study is the susceptibility of other human cancer cell lines to induction of proliferation by physiological concentrations of thyroid hormone.

Acting via a cell surface receptor, thyroid hormone is a growth factor for glioma cells

Recent evidence suggests that the thyroid hormone L-thyroxine (T4) stimulates growth of cancer cells via a plasma membrane receptor on integrin alphaVbeta3. The contribution of this recently described receptor for thyroid hormone and receptor-based stimulation of cellular mitogen-activated protein kinase [MAPK; extracellular signal-regulated kinase 1/2 (ERK1/2)] activity, to enhancement of cell proliferation by thyroid hormone was quantitated functionally and by immunologic means in three glioma cell lines exposed to T4. At concentrations of 1 to 100 nmol/L, T4 caused proliferation of C6, F98, and GL261 cells, measured by accumulation of proliferating cell nuclear antigen (PCNA) and radiolabeled thymidine incorporation. This effect was inhibited by the T4 analogue, tetraiodothyroacetic acid, and by an alphaVbeta3 RGD recognition site peptide, both of which block T4 binding to integrin alphaVbeta3 but are not agonists. Activation of MAPK by T4 was similarly inhibited by tetraiodothyroacetic acid and the RGD peptide. The thyroid hormone 3,5,3'-triiodo-L-thyronine (T3) and T4 were equipotent stimulators of PCNA accumulation in C6, F98, and GL261 cells, but physiologic concentrations of T3 are 50-fold lower than those of T4. In conclusion, our studies suggest that glioblastoma cells are thyroid hormone dependent and provide a molecular basis for recent clinical observations that induction of mild hypothyroidism may improve duration of survival in glioblastoma patients. The present experiments infer a novel cell membrane receptor-mediated basis for the growth-promoting activity of thyroid hormone in such tumors and suggest new therapeutic approaches to the treatment of patients with glioblastoma.

Molecular targeting and treatment of EGFRvIII-positive gliomas using boronated monoclonal antibody L8A4

PURPOSE

The purpose of the present study was to evaluate a boronated EGFRvIII-specific monoclonal antibody, L8A4, for boron neutron capture therapy (BNCT) of the receptor-positive rat glioma, F98(npEGFRvIII).

EXPERIMENTAL DESIGN

A heavily boronated polyamido amine (PAMAM) dendrimer (BD) was chemically linked to L8A4 by two heterobifunctional reagents, N-succinimidyl 3-(2-pyridyldithio)propionate and N-(k-maleimidoundecanoic acid)hydrazide. For in vivo studies, F98 wild-type receptor-negative or EGFRvIII human gene-transfected receptor-positive F98(npEGFRvIII) glioma cells were implanted i.c. into the brains of Fischer rats. Biodistribution studies were initiated 14 days later. Animals received [(125)I]BD-L8A4 by either convection enhanced delivery (CED) or direct i.t. injection and were euthanized 6, 12, 24, or 48 hours later.

RESULTS

At 6 hours, equivalent amounts of the bioconjugate were detected in receptor-positive and receptor-negative tumors, but by 24 hours the amounts retained by receptor-positive gliomas were 60.1% following CED and 43.7% following i.t. injection compared with 14.6% ID/g by receptor-negative tumors. Boron concentrations in normal brain, blood, liver, kidneys, and spleen all were at nondetectable levels (<0.5 microg/g) at the corresponding times. Based on these favorable biodistribution data, BNCT studies were initiated at the Massachusetts Institute of Technology Research Reactor-II. Rats received BD-L8A4 ( approximately 40 microg (10)B/ approximately 750 mug protein) by CED either alone or in combination with i.v. boronophenylalanine (BPA; 500 mg/kg). BNCT was carried out 24 hours after administration of the bioconjugate and 2.5 hours after i.v. injection of BPA for those animals that received both agents. Rats that received BD-L8A4 by CED in combination with i.v. BPA had a mean +/- SE survival time of 85.5 +/- 15.5 days with 20% long-term survivors (>6 months) and those that received BD-L8A4 alone had a mean +/- SE survival time of 70.4 +/- 11.1 days with 10% long-term survivors compared with 40.1 +/- 2.2 days for i.v. BPA and 30.3 +/- 1.6 and 26.3 +/- 1.1 days for irradiated and untreated controls, respectively.

CONCLUSIONS

These data convincingly show the therapeutic efficacy of molecular targeting of EGFRvIII using either boronated monoclonal antibody L8A4 alone or in combination with BPA and should provide a platform for the future development of combinations of high and low molecular weight delivery agents for BNCT of brain tumors.

Central Nervous System Cancers Clinical Practice Guidelines in Oncology

In the year 2005, an estimated 18,500 new cases of primary brain and nervous system neoplasms will be diagnosed in the United States. These tumors will be responsible for approximately 12,760 deaths. The incidence of primary malignant brain tumors has been increasing over the past 25 years, especially in elderly persons (rates are increasing at about 1.2% each year). Metastatic disease to the central nervous system (CNS) occurs much more frequently, with an incidence about 10 times that of primary brain tumors. It is estimated between 20% and 40% of patients with systemic cancer will develop brain metastases.

For the most recent version of the guidelines, please visit NCCN.org

Boronated epidermal growth factor as a delivery agent for neutron capture therapy of EGF receptor positive gliomas

The purpose of the present study was to further evaluate a boronated dendrimer (BD)-epidermal growth factor bioconjugate (BD-EGF), administered by means of convection enhanced delivery (CED), as a molecular targeting agent for boron neutron capture therapy (BNCT) of the F98(EGFR) glioma. Twenty-four hours following CED of (125)I-labeled BD-EGF 47.4% of the injected dose (ID) was retained in F98(EGFR) gliomas compared to 12.3% in F98(WT) (wildtype) receptor negative tumors. Normal brain values were in the range of 5.9-10.1% ID in the tumor bearing cerebral hemisphere. Boron concentrations in F98(EGFR) gliomas were 22.3 and 11.7 microg/g following CED and i.t. injection, respectively. Based on these results, BNCT studies were initiated at the Massachusetts Institute of Technology nuclear reactor (MITRII). The mean survival time (MST) of rats that received BD-EGF either alone or in combination with boronophenylalanine (BPA), injected i.v., were 53+/-13 d and >61+/-14 d, respectively, compared to 40+/-5 d for BPA alone and 31+/-4 d for irradiated controls. These data show that CED improved the radiobiological effectiveness of BD-EGF and lay the groundwork for future studies using combinations of boron delivery agents for NCT of EGFR(+) gliomas.

Dosimetric accuracy of a staged radiosurgery treatment

For large cerebral arteriovenous malformations (AVMs), the efficacy of radiosurgery is limited since the large doses necessary to produce obliteration may increase the risk of radiation necrosis to unacceptable levels. An alternative is to stage the radiosurgery procedure over multiple stages (usually two), effectively irradiating a smaller volume of the AVM nidus with a therapeutic dose during each session. The difference between coordinate systems defined by sequential stereotactic frame placements can be represented by a translation and a rotation. A unique transformation can be determined based on the coordinates of several fiducial markers fixed to the skull and imaged in each stereotactic coordinate system. Using this transformation matrix, isocentre coordinates from the first stage can be displayed in the coordinate system of subsequent stages allowing computation of a combined dose distribution covering the entire AVM. The accuracy of this approach was tested on an anthropomorphic head phantom and was verified dosimetrically. Subtle defects in the phantom were used as control points, and 2 mm diameter steel balls attached to the surface were used as fiducial markers and reference points. CT images (2 mm thick) were acquired. Using a transformation matrix developed with two frame placements, the predicted locations of control and reference points had an average error of 0.6 mm near the fiducial markers and 1.0 mm near the control points. Dose distributions in a staged treatment approach were accurately calculated using the transformation matrix. This approach is simple, fast and accurate. Errors were small and clinically acceptable for Gamma Knife radiosurgery. Accuracy can be improved by reducing the CT slice thickness.

Stereotactic gamma knife surgery for trigeminal neuralgia: detailed analysis of treatment response

Object. The purpose of this study was to assess the durability and completeness of pain relief in patients treated using stereotactic gamma knife surgery (GKS) for trigeminal neuralgia (TN).

Methods. Thirty-eight patients with refractory TN were treated with stereotactic GKS. All patients received a prescription radiation dose of 35, 40, or 45 Gy to the 50% isodose surface through a 4-mm collimator helmet. The group was assessed regularly based on physician-directed interviews for a median follow up of 24 months (range 6–27 months). Pain relief was classified as excellent (no pain without medication), good (well-controlled pain with continued medication), fair (decreased but residual pain with continued medication), or poor (unimproved or increased pain with the same or increased medication).

Three months after treatment, pain relief was good or excellent in 71% of patients. By 24 months post-GKS, 50% of the original cohort had poor pain relief, 21% continued to have either excellent or good relief, 3% had fair relief, and 26% had not reached the 24-month follow up. Based on their status at the last follow up, 29% of patients had excellent and 16% had good pain relief. Thirty-seven percent experienced facial numbness, which was dose related. In addition, there was a significantly higher rate of complete pain relief in patients who had facial numbness following treatment (p = 0.003).

Conclusions. Stereotactic GKS is an effective treatment in patients with TN; however, the durability of pain relief and the time to treatment response are limiting factors. As with other types of ablative treatment, facial numbness is strongly associated with better treatment response.